Effect of exogenous melatonin on the antioxidant defense system in the liver and small intestine of the Syrian hamster (Mesocricetus auratus)

Background. Due to the growing light pollution and the development of new territories, including northern ones, the search for drugs that increase the adaptive capacity of the organism is promising.The aim. We studied the effects of the exogenous melatonin (100 µg/day/animal) on antioxidant status of liver and small intestine in Syrian hamsters (Mesocricetus auratus) in the light conditions of North-West of Russia (Petrozavodsk, northern lighting – NL).Materials and methods. Female hamsters were exposed to a 12/12 light/dark cycle (LD; n = 12) or NL for 3 months. In NL light conditions hamsters were divided into two groups: NL-control (received placebo; n = 12) and NL-mel (received melatonin; n = 12). The study was conducted from the period of the summer solstice – June 25 (NL: 19.36/4.24) to September 25 (NL: 12/12) (autumn equinox).Results. Animals were kept in the NL conditions had decreased the levels of GSH and activities of antioxidant enzymes (superoxide dismutase (SOD) and catalase) at initial stage of experiment as well as increased TBA reactive substances (TBARS) level at the beginning and after a month of the experiment in the liver in comparison to control (LD). It was observed that in the small intestine the activities of SOD and the levels of GSH (initial and intermediate stages) and TBARS (end of the experiment) were significantly higher in NL in comparison to LD. Liver and small intestine TBARS concentrations after one and three months of the experiment were decreased in NL-mel in comparison to NL-control.Conclusion. The results of the study indicate the sensitivity of the antioxidant defense system in the tissues of the liver and small intestine of Syrian hamster to the photoperiod and exogenous melatonin. The present study revealed that exogenous melatonin was able to reduce the level of TBARS and increase the activity of SOD and CAT in the light conditions of North-West of Russia

The modulating effect of coat color mutations on the generation and neutralization of reactive oxygen species in the Аmerican mink (Neovison vison) as a model

The influence of gene mutations encoding coat color on parameters of reactive oxygen species (RO S) generation and neutralization in six organs of the mink (Neovison vison) was evaluated. The study was conducted with standard dark brown (+/+), monorecessive royal pastel (b/b) and silver-blue (р/р), and direcessive sapphire (a/a р/р) mutant minks. It was found that the functioning of both RO S generation and neutralization systems was genotypespecific. The direcessive sapphire (a/a р/р) combination induced high levels of antioxidant enzymes’ activities as well as of thiobarbituric acid-reactive products (TBА-RPs), characterizing lipid peroxidation level. In heart tissue, coat color mutations exerted modulating effects on both RO S generation and the level of low-molecular-weight antioxidants. The royal pastel (b/b) genotype showed the highest level of RO S generation, and the sapphire (a/a р/р), the lowest (statistically significant difference from standard). Coat color mutations modulate the dintensity of RO S generation and neutralization in lung tissue. On the one hand, royal pastel (b/b) in comparison with standard dark brown (+/+) decreases the total level of RO S generation, and on the other hand, it increases the level of generation of superoxide anion-radicals. Cluster analysis, presented in a combined dendrogram, showed that royal pastel (b/b) and sapphire (a/a р/р) minks, the farthest from standard (+/+), had the greatest modulating effects. It is reasonable to suggest that such effects contributed to the genetic plasticity of American mink in the course of colonization of North America and then during mink introduction in Northern Eurasia and South America